Impact of active dose management on radiation exposure and image quality in computed tomography: An observational study in 1315 patients.

PURPOSE

To determine the clinical impact of CT dose management team on radiation exposure and image quality.

METHODS

2026 clinical routine CT examinations of 1315 patients were evaluated retrospectively. A CT dose management team was established as an integral part of the radiological department. It identified 5 CT protocols (A-E), where national reference values were exceeded the most. Those reference values included specifically the mean volumetric CT dose index (CTDI) and the mean dose-length product (DLP). Baseline data (period 1) and follow up data (period 2) were obtained after reduction of tube voltage and increase of pitch or noise index. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated to compare image quality. Two-sided t-tests were performed.

RESULTS

Mean CTDI and mean DLP of the chest protocol (A) decreased after reduction of tube voltage (P < 0.01). In the chest/abdomen/pelvis protocol (B), the increase of noise index resulted in a significant mean CTDI decrease (P < 0.02) without statistical significance of mean DLP (P < 0.12). In the abdomen/pelvis protocol (C), mean CTDI (P = 0.01) and mean DLP (P < 0.01) were significantly lower after noise index increase. In the staging of hepatocellular carcinoma (D), mean CTDI and mean DLP were significantly lower after increase of pitch and noise index (P < 0.01). The lung protocol (E) yielded no significant changes after modulation (P > 0.05). SNR (protocol A) was significantly higher in period 2 (P < 0.04). Protocol D showed significantly lower selected SNR and CNR (P < 0.02).

CONCLUSIONS

Establishing an operating dose management team as a standard for good clinical practice helps to considerably reduce CT radiation dose while preserving image quality.